


Summer Heat calls for new Attire

by cr3stfallen



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: DLC Byleth, F/M, First Time, Jealousy, Porn With Plot, Pre-Time Skip, Semi-Public Sex, Sexual Fantasy, Smut, Summer Outfits are SO DAMN CUTE, Teacher-Student Relationship, Vaginal Fingering, marking his territory, sassy Sylvain is the best instigator
Language: English
Status: Completed
Published: 2019-11-21
Updated: 2019-11-21
Packaged: 2021-02-26 02:29:28
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 4,848
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21516076
Author URL: https://archiveofourown.org/users/cr3stfallen/pseuds/cr3stfallen
Summary: Two parter~ First is Dimitri's fantasy towards her (summer DLC uniform), second part is hers towards him (butler uniform and NG+ hair)Pre- then Post- skip respectively, with maybe them confessing later LOLI just really love thick ass Byleth and protective Dimitri
Relationships: Dimitri Alexandre Blaiddyd/My Unit | Byleth
Comments: 13
Kudos: 226





	Summer Heat calls for new Attire

Zoning out while waiting after the bell dinged above one early morning, Dimitri snapped back to his classmates causing an unexpected stir.

"Wow Prof you might kill someone with that thigh action~" Sylvain quipped with a whistle, Mercedes cooing in admiration at their teacher's apparent change. 

The prince whipped his head around to check what was going on and very quickly regretted it. There she was, Byleth in all her glory in a tightly fitted tan summer uniform, tights, and glasses. Glasses? They were  _ very cute…. _ Not to mention her fluffy blue locks pressed by a headband in pink to compliment it. His eyes went wide as the class continued to question her walking in late, looking like she belonged with the rest of them nonetheless. Why change now?

"A-any reason for the new wardrobe, Professor?" Ashe called gently and she lightly smirked with a flat tone quickly back as she set her materials down. 

"Ah… yes. My armor needed repairing and I had to ask to borrow something for today. Sorry I'm late because of this, I am glad you all find this outfit so interesting."

_ Interesting…. well…  _

He thought to himself.

_ More than that. Downright adorable. There is an innocence about it her normal attire lacked. Innocence I want to defile. _

Gulping down hard, he risked a compliment that hopefully concealed his true feelings in front of his already suspicious classmates while she continued reading for the lecture. 

"I quite like it. You fit right in with us! Isn't that what you desired?" 

Annette quickly agreed with a giggle and hop in her seat. "Ooooh, I know!!!! You look ADORABLE in those socks. I wonder if you'll trick any of the staff with it." 

_ The socks….  _

He risked a stare as she wrote on the chalkboard. 

_ Oh.. oh my gods… the socks. They weren't stockings….  _

Ending mid-thigh, Dimitri had failed to note the small gap of milky exposed flesh, gulping hard as he wondered how they stayed up on her shapely legs, or…. 

_ Or how they would feel around my head… _

Byleth chuckled lightly, apparently amused at the thought of Hanneman babbling about while she looked all the part innocent schoolgirl like they all did. At the very least, the attire was a perfect fit for the weather, unlike his too tight all-black outfit clad in armor that grew hotter by the minute. 

"I guess you're right, that would be a fantastic prank. I'm sorry for the distraction again but I'm already late and I don't want Stuffy Professor Crest to whine about my work ethic again."

Face flush, he pretended to write notes lazily as his mind wandered dangerously. This uniform  _ did _ cover different parts of her form, true, but it was the quality of that skin that really ruined him. Clearing his throat, he hunched over to try and hide the furious blush forming as he rehearsed exactly what he wished he could do with the new attire. Stain it. Rip it. Ask her gently for admission, slipping long bare fingers gently under her underwear with a kiss, grasping at the hardened muscle underneath with a hitch in her breath. 

He longed to see it so badly that he lost touch with his surroundings for a moment. How easy it would be to beg his sweet instructor to teach him here, legs splayed for him on the desk as he ground his manhood into her painfully hot underclothes, skirt hiked up between the two as she whined sweetly into his ear with every touch. Shaky hands massaged at her confined mounds before she silently, slowly,  _ painfully slow,  _ unbuttoned the front of her shirt with intent in those beautiful purple eyes. The intense focus he was lucky to glimpse in battle for fleeting seconds, now centered entirely on destroying his resolve instead. 

_ "Please…. my love… I need you…."  _ he cooed sweetly for her, brow furrowed with desperation as his heart pounded.

_ "Where, my sweet Dimitri~ on your desk? Where we could get caught?"  _

Nibbling at her ear with a moan, he gruffly returned the inquiry.  _ "Isn't that part of the fun..."  _

Knowing how selfish it all was just made the sin all that much sweeter. If only they were equals like Annette had mused. If only.

Then he wouldn't need to wrack himself with further guilt every time he succumbed to base needs late at night. He could simply ask her to dance, or court properly, sneaking small moments in secret before announcing their courtship. But no. 

Of course not. Dimitri Alexandre Blaiddyd never did things the easy or happy way. So thus he sat here, pining for things out of his reach socially, as she casually walked back and forth just feet away from him in the sultry summer uniform. He hoped none of the other students would notice him straining to stay hidden by his desk, tight pants only growing more uncomfortable by the second as he continued along his depraved path internally. She seemed not to notice the…  _ special attention _ he was giving her form as she walked by, to his minor relief at least. Byleth swiped a small hand to push hair back behind her ear and again he imagined his hand doing so instead, whispering sweet nothings to her as he grasped her soft thighs and left love notes along her exposed neck trailing down to the newly discovered collarbones underneath her shirt.

A soft whine escaping her throat as his hands roamed up to her soft exposed breasts, massaging the day's woes out on her pert nipples inside the opened shirt. Dimitri cradled one heavy mound before engulfing it with his mouth, losing himself in her soft scent he had only thus barely noticed as she passed by before as she nuzzled closer to him squishing herself against his chest. He stopped, ripping off his top and casting it wantonly to the side before quickly returning to her soft bosom again.  _ "I'm sorry I just… I need to feel you… closer…"  _

A soft moan as Byleth's face crinkled, grasping at the small of his neck to urge him on. Biting at her pebbled pink nip, he glanced up to catch her brow furrowing ever so sweetly for him. If only… he could see it for real…. 

"Hey… Dimitri!" He snapped back to her leaned over his desk altogether too close, jumping away in embarrassment. Her white shirt still firmly buttoned, skirt still firmly in place, her hand resting near to his own, and a subtle frown nobody else would have perceived painting her features as she tried to read him. He shook his head at the ground to avoid her questioning gaze.

"G-gods I apologize. I do not know what has come over me today. Perhaps it is the heat. I… do not do well in humidity." 

"It’s fine. We are doing paired projects, for now, to see who can come up with the best gambit assignments on the board." 

He blinked quickly, looking around for who he was with. Annette and Mercie. Sylvain and Felix. Ingrid and Ashe. Dedue had moved to another table with the new recruit Bernie. And that left himself. 

"I… um. I'm sorry I wasn't paying attention, I can work on my own." Pursed lips as he clenched his fists tight before she walked around and plopped down in the chair next to him instead, kicking her  _ muscular thighs _ upon his table. 

"I'm here if you have questions. Or we could just partner up and ruin their chances." He glanced over and thought he saw a smirk. "You know. Since I have the answers." 

_ Partner??? we….  _ His breath caught in his throat at that, unable to break his staring at her legs propped up and crossed in that too-short skirt. She really did not know how to act like a proper lady. It would be the death of him. 

"Pardon me, but doesn't something like this have no correct answer in the end? It all depends on the strengths and weaknesses of your allies how you want to play a gambit up. Working together always has better results at any rate." 

Byleth caught his eye with her subtle smile as she placed a hand at her chin. 

"I wasn't gonna tell you that, but yeah. And here you are wondering if you're fit to be King someday. Leadership skills are probably a good asset for that, right?" 

He could not keep the flush from hitting his face at the compliment, stammering for a response before Sylvain hopped up in front of the desk with a question. Before he could start thought, the prince caught him trying to catch a glance up her skirt. 

“Hey Professor, what do you think about switching Annette to dancer corps gambit? She just meets the requirements  _ and _ you often keep her near us for rallying anyway so why not make her the ultimate cheerleader?” 

He slowly tongued at the inside of his cheek while continuing to stare at their teacher's legs, raising an eyebrow at Dimitri quickly growing more enraged. Byleth seemed not to notice at all, however, as she glanced at the blonde instead before snapping back to the query. 

“Oh? Hm? I… suppose so. My only worry is we don’t have many high ranking mages with all you rowdy physical boys to rain down damage on groups with low resistance. Maybe once we raise  _ your  _ reason ranking some to cover that gap we could consider it…” she seemed to actually be contemplating the validity of the idea as she stared at the ceiling tapping a finger on her exposed thigh. Professor was always fidgety when she was thinking, near imperceptible narrowing of her eyes as she looked the redhead up and down to see if he had anything else to say. 

“Oh! I. Sorry. That’s all. I’ll let you two get back to it.” He winked with a start before jumping back to his seat. Dimitri knew better, turning his head as Sylvain passed to scoff at him. However, their time was shortly over as he worked in silence next to her as she softly hummed and picked under her fingernails absently, bobbing one tiny foot on the table still. It was… terribly, painfully hard to focus when she was being so unintentionally cute. He ended up not getting much done in the end after all before she broke the time to share answers and critique ideas. 

She was right. A lot of fresh ideas, none inherently good or bad save one from Sylvain probably thrown as a joke to annoy everyone, and they broke for lunch shortly thereafter. Thank Sothis for that. He no longer had to suffer his racing thoughts making any rational thought completely impossible. 

Sitting in the dining hall, however, ended up not being as safe a haven as he had hoped. Professor stayed behind for a short while to work on things, yes, but Sylvain had sat suspiciously close across from the Prince with a knowing smirk. Gentle clinking of silverware as he hoped for the best before Sylvain loudly said with pride, “They’re black, if you’re wondering.” 

_ “What’s _ black?” 

“Her underclothes. I saw you staring so I thought I’d do you a favor and answer the question.” 

“I! I was not staring!” 

_ BLACK??? Her underclothes??? WHY would he tell me this?? I was struggling so hard… to… her… I…  _ he gulped hard as he saw them in his mind, her tiny hand running over the flimsy fabric covering her womanhood. The black fabric betraying the wet glint soaking through...

“Oh my goddess, you are so oblivious. Well. Anyway, you know what black signifies right?” 

He didn’t wish to know. It probably didn’t mean anything anyway. Sylvain just spouting nonsense again. Dimitri stayed silent as he tried drinking to clear his tight throat before choking at his answer.

“It usually means the ladies are more  _ open and willing _ if you catch my drift.” 

Dimitri slammed his hands down on the table between them with feverish intensity, looming over the man across from him with murderous intent behind his sky blue eyes.  _ Never mind how Sylvian had been brazenly staring at the object of his affection, but disrespecting her by insinuating that she was loose with her affections? Was this supposed to please him? _ His jaw tightened as he tried to stop his negative thoughts to little effect. 

"Now I know you aren't implying anything inappropriate about her. It would be gravely misguided of you to taunt me so." 

Sylvain simply chuckled as he leaned back with a smirk.

"I wouldn't dream of it,  _ your highness _ . Just saying it might not be long before a snack like her is snapped up by those bolder than you."

-

Later in the school day, long after classes had let out, Dimitri could not bear to part from his desk to ask Byleth some questions,  _ naturally. _ He had made it through the rest of the lecture without losing his head again but did not want to leave before the playboy simply for the taunting earlier.  _ He was just keeping her safe from his advances, that was all. _

_ Nothing suspicious.  _

Certainly not staying to stare at her longer, even as the temperature dipped in the evening hours and the crowds slowly died down near the classrooms till the summer crickets and cooling breeze were their only companions. He had discarded his gloves and cape somewhere along the way, sweat making his study a bit too tedious as he tried to catch up from what he had missed earlier. She did not seem to mind him staying behind, lazily grading in silence nearby with a hand propping her head up and her glasses slowly slipping. With a sigh, she rose to grab a book for reference from the shelves beyond his seat, bouncing lightly as she passed with short boots clicking along the stone floor. His eyes followed her, pausing to watch her climb the flimsy ladder and try reaching something too far out of reach. 

"Oh wait let me help." He jumped up immediately to steady the moveable ladder before she could hurt herself. 

"Thanks… I probably should have asked but I didn't want to bother you." 

He turned his head up to answer before accidentally catching a glance up her skirt from the unforgiving angle far above where he stood.

"It's no bothe-" 

His eyes went wide. 

_ Black. They were black. He was right.  _

His eyes went wide and reaction flashed through his body before he could realize what was happening, his grip tightening on the moving ladder and shattering it instantly, crunching wood and a surprised yelp punctuating the air. Before either knew what was happening, she had fallen right on top of him, thudding to the ground as he broke her fall while the wind was knocked out of him from her body weight. A groan, his eyes shut in pain and shock while she tried to steady herself shakily. 

“I… are you alright? I’m so sorry I don’t know how that happened…” Words failed him, opening his eyes to see her bewildered face close enough for her breathing to hit him.    
  
“You broke my fall so I think so. Is your head alright?” She still hadn’t moved from her spot in his lap, instead lifting a hand to check where his skull had bonked the stone floor. This absolutely was not helping the cause of the accident in the first place. 

_ Too close... My resolve is going to snap... If she… Why hasn’t she moved? _

His mouth agape, she caught his gaze with those soft amethysts and his breath caught in his throat. Her soft hand at his hair, he couldn’t find the words to answer her question like this. A small sting, but he was sure no actual issue other than a goose egg tomorrow. 

“I’m… fine… fine... I should…” 

_ He should get up and leave like a gentleman. This was unbecoming of a prince.  _

He risked a move instead, brushing his hand gently up her exposed leg while maintaining eye contact to gauge her reaction. Byleth’s eyes just softened mouth parting slightly. 

“I could get in trouble…” barely a whisper, but she did not stop him. 

“Yet I couldn't live with myself if I failed to act on this...” 

_ If I lost you to someone undeserving. _

Her brow furrowed, soaking in his beautiful face with a tiny hand resting on his chest. Her breath sped up with a gulp. His other hand joined to match on the other leg, inching upwards under the tight hem painfully slow. Her eyelashes fluttered, softening against the touch as she refused to stop searching for an answer he didn’t have in those intense eyes. Dimitri’s heart was pounding, waiting and hoping for her to move next as they lay amongst the mess of scattered wood on the floor. 

Byleth’s resolve broke silently as her head dipped down to place a gentle kiss on him, and that was it. Immediately the two intensified things, unbroken lips testing each other out for the first time as he grabbed at her thighs for any tether to the world around them. Lost in each other, her hands held his face shakily as their breathing sped up, his fingers digging further towards the goal that had been ruining his fantasies all day before he grabbed roughly at her half-exposed derriere. A soft whine betrayed her, grinding down on him instinctually and goading him on further. Soft teal waves fell onto his face as the heat pooled deep in them, hands gently moving to glide up her back and hold her tightly around the small of her waist. 

Breaking the kiss, she pushed his face to gain access to his neck, gently nibbling along the exposed skin that betrayed his racing pulse before tugging on an earlobe. That earned her a gentle gasp from him; still utterly surprised that she was so eager and still utterly terrified of making a wrong move.

This entire affair was risky, and that wasn't accounting for how easy it would be for any fellow classmates to wander in on them currently stuck on the cool floor together. At the very least the stone below was stopping him from overheating as she lavished praise on the sensitive skin under his jaw, unintentionally tensing under her affections. 

"I had a feeling you had been staring at me all day." 

_ How could I not?  _

"Am I that transparent?" 

"Terribly." 

He pushed her back gently to sit up, mouth tensing with worry again as his bare hands wandered back down, dipping inside the black panties with furious intent. 

"I was worried you would find this unwelcome, or reject me for another…" 

Byleth hummed softly, falling to knock foreheads with eyes closed. She was so painfully difficult to read most times, but this moment showed a blessed delicacy from her. Pressing small kisses on her face, he kneaded the toned backside that had tortured him for half a year. 

"What? Are you worried about Sylvain? I could never." 

His eyes darkened.

"Prove it." 

Byleths eyes fluttered open in confusion, flitting between one blue eye to the other.

"How?" 

His manhood twitching against her heat betrayed his selfish hopes. He broke eye contact, shakily continuing.

"Let me… let me prove a point…" 

His Professor giggled softly, drawing his embarrassed gaze back. _Was that a no?_ _Idiot. Idiot. You know better than to ask for this. That is not yours to take._

"I didn't know you could be this jealous and bold, Dimi…" she said as she pressed her soft chest to his, silently cursing the molded armor that prevented the sensation from hitting him. 

_ You are not taking this. She is giving it. That nickname…  _

Byleth kissed him deeply as a response, pushing her way into his mouth with a gasp to battle with their tongues roughly. This was too much. He paused, pulling himself off the floor and deftly yanking her into his arms while she continued locking lips, striding across the room before plopping her gently on Sylvain's desk, legs splayed. The silent request dawned on her, a deep flush finally making her cover her smirking cheeks. His patience gave out, yanking the tight tan skirt up to gain access to her womanhood before grinding himself against it. So painfully warm, even through the layers he wore. 

Layers. It was too hot. 

Keeping their kiss going, his fingers fumbled at this jacket zipper before peeling it off and dropping it beside where he stood, returning to grab at her nearly bare chest through the white topstitched dress shirt that so neatly propped up her ample bust. Mewling, Byleth stopped him to unbutton the front of it for him frantically, him accidentally popping the last button off in white-hot need before his calloused grip found purchase on the sensitive forbidden skin. Thumbing over an already hardened nipple, she arched into the touch desperately, twitching gently and gasping at the new sensation. That only made it harder for him to hold back, biting roughly at her newly exposed collarbones, lathing over the fresh teeth marks before sucking harder at the pain pricked flesh. 

Her fingernails dug across his shoulders as he groaned, grabbing her hips with his free hand while he continued to make sure she would not forget her promise with more love bites. Moving downward, he finally engulfed one soft mound greedily with his mouth while groping deeper into her ass crack with one hand. Devilishly soft, just as he had hoped, perfect for sucking at her hardened nipple until she was whining for mercy with a rough tug on his blonde locks. The skin was starting to flush across her chest, peppered with his glorious handiwork as he pulled back. 

Giving no time for doubt, a tiny hand grabbed desperately at him, guiding him to the growing arousal of slick readily apparent through those damned black panties. He noted now they had an adorable echo of the motif that was across all their outfits. So it wasn't her choice, then. This was made for the uniform, not her signaling her eagerness. It seemed that wasn't the only thing about her Sylvain had an incorrect assumption over, he thought as he grinned through messy bangs to rub gently on her mound at her behest. 

  
  


_ She was eager for him at least. Only him. _

He couldn't wait any longer before feeling her soft confines for real, after all this time able to speak truth to his hidden desire with a gentle yank. Accidentally tearing the poor underwear straight in two, rather than dragging it down her legs, she gasped in surprise and slight upset.

"I am so sorry I just… can't help myself around you Byleth…" 

She moaned as his hand quickly found her slit, massaging up and down the folds with needy certainty.

"Call me that again…"

His gaze lifted from her exposed and crumpled skirt hiked up, heavy breasts heaving and arms braced back against the redhead's desk to the furious blush now steadfast over her pale cheeks. Sinking one finger inside her, he continued.

"Call you what, dear Professor." 

Her face crumpled ever so softly, whining and pushing herself further into his hold. The soft wet walls pulsed around his long finger begging for more. No answer from her. He added another finger, pumping as gently as his focus would allow, dragging delectable small changes in her face out from each thrust.

"By- _ haaaaaa….."  _

She grabbed desperately at his shoulders as he hit something good deep inside her, pressing upward and intently soaking in all he could as his own arousal begged for attention. Withdrawing his fingers, curiosity made him suck her juices from them as she watched. Regrettably, it hardly had any taste for him due to his lack of any in general but it smelled so musky, alluring. Enough to drive him wild. Pulling back he freed himself from his too-tight pants, leaving it pooled at his feet as he lined his head up to her sex. Gulping hard, he kept his gaze intently on her for approval for a few heavy seconds. 

"What about  _ mine… _ Can I call you that?" 

Her large eyes stared back at that, mouth slightly parted in expectation and a newfound delicacy never before seen as well. Reaching up, she pulled his face to her own for a gentle kiss as he slowly sunk into her, groaning against her mouth as he sat flush against her own hips. It felt so wrong, so right. Nothing felt so comforting and electrifying at the same time, her walls clenched tight around his length as he stilled, adjusting both of them to the overwhelming feeling. Her soft legs wrapped tightly around his backside, holding close to his neck before he slowly pulled back and snapped in again, gauging her response delicately for any sign of discomfort. Instead, she just sighed into his shoulder and gripped him tighter, feeling his pulse ringing heavy through him as her touch burned. Again, pulling back and slamming in again, another soft sound from her. 

Quickly, his pace gave break to frantic intensity, still careful not to push her past pleasured pain to actually hurt as he pounded into her welcoming confines, ridged walls pulling so many more waves of goosebumps up his spine than his pathetic hand ever could. His breath hitched as he continued to claim her for his own, begging for her own happiness as well with each intent laden glance to check on her. Head threw back, she whined and moaned loudly, kneading at any skin she could grab at, prickling at him with raking nails begging for more of his pulsing length filling her to the brim. The heat was nearly unbearable, head rush hitting him hard as he felt the tension pooling deep in his chest.

He slowed, however, pushing down his own needs to reach down and yank on one already abused bud on her chest, holding for dear life onto her thick ass as he ground purposefully into her clit as much as possible. That definitely helped, her yelps breaking the heavy panting between them raising the hairs on his neck. Only he could hear this song. Only he could see this dance. 

"Byleth... I…." his broken voice stuttered as he continued with his composure quickly crumbling.

"M-me too- _ ah~ it's oka~hhhhhaaa…."  _

That was enough permission for him. The gentlemanly front broke its last thin straw, grabbing at her hips and fucking into her with reckless abandon until he found his end, pulse ringing in time with his spilling deep inside her, overly stimulated tip intensely glad at the release of the tension that had built between them. She pulled almost too hard at his hair with a loud moan as she twitched around him shortly after, brow furrowed in ecstasy. 

_ Only for me. _

Catching his breath, shaky arms allowed him to crumple against her shoulder and steady himself. Normally so strong, perhaps the emotional release exhausted him. they did not wish to break the connection but eventually, he was forced to withdraw wilting from her and marvel at the mess they had made. His hair disheveled and sweat beading lightly across his brow, pants still tangled around his feet; her skirt crumpled in a bunched up strip at her waist, shirt yanked open haphazardly and hair mussed up to match the blush still stuck to her. And the hickeys. He lightly brushed across them, marveling at it while she shivered while failing at staring boldly at his naked form.

"Perhaps this attire was more dangerous than I thought." She chuckled into her hand, finding humor at how easily he had crumpled for her at the hint of leg. His hands drifted down to trace over them, noticing hints of fingerprints he accidentally left across the backs of her thighs. 

"Minx…" He halfheartedly teased back, a soft glint in his eyes.

"You can't blame me for your lack of self-control,  _ Your highness. _ " 

He pulled her back to him with a pout, his spend slowly falling out onto Sylvain's table beneath her. 

"You know I hate being called that… but maybe he will think twice about taunting me now." 

They quickly gathered themselves, pulling her off the wooden desk gently and helping her right herself realizing that they were still, in fact, right in plain sight through slightly tinted stained glass. They got to her discarded underclothes, realizing they were entirely ruined unsure of where to stash them. Leaving for the night, Byleth paused to stuff them in the drawer under the redhead's desk with a hearty laugh before running out of the classroom. 

\- 

However, he woke with a start to find himself sweaty, rock hard, and still sadly in his room having not acted on a single thing after Sylvain had told him that information. Shame overcame him as he turned over in bed to finish the job before his dreams of her could fade too quickly. Maybe someday he would have the bravery to speak up... Someday. Not today. 

  
  
  



End file.
